1. Field of the Invention
The present invention relates to an ion implanting apparatus and, more particularly to an SiMOX (Separation by Implanted Oxygen) ion implanting apparatus suitable for implanting oxygen ions into a silicon wafer.
2. Related Background Art
An ion implanting apparatus for oxygen ions into a silicon wafer having been known is that a plurality of wafer holders are fixed onto a rotating disk arranged inside a process chamber (a vacuum container), a disk-shaped silicon wafer being fixed onto each of the wafer holders, an ion beam from an ion source being irradiated on each of the silicon wafers while each of the silicon wafers is being rotated as the rotating disk is being rotated. The ion implanting apparatus of such a kind employs a holding structure disclosed, for example, in Japanese Patent Application Laid-Open No.61-116746 for fixing a silicon wafer onto the wafer holder. The holding structure is that the wafer holder is fixed in an inclining state to a rotating surface of the rotating disk, the silicon wafer being placed on the wafer holder, the silicon wafer being held down onto the wafer holder by a component of a centrifugal force caused by rotation of the rotating disk. In other words, the ion implanting apparatus employs the holding structure for holding the silicon wafer onto the wafer holder under a state that a reverse side surface of the silicon wafer is in contact with the disk-shaped wafer holder. When a silicon beam by oxygen ions is implanted into the silicon wafer, the silicon wafer is heated, for example, up to 600xc2x0 C. using a heater in the process chamber, and then the ion beam is irradiated onto the silicon wafer to form an insulation film in the silicon wafer.
That is, in the SiMOX ion implanting apparatus, since it is necessary that the ion beam is implanted into the silicon wafer with a high voltage and a high current after the silicon wafer is heated up to a high temperature, the method employed is that the silicon wafer is initially heated up using the heater, and then the ion beam is irradiated onto the silicon wafer. In this case, control for keeping the silicon wafer at a constant high temperature condition is performed by heating by the ion beam and at the same time by adjusting an output power of the heater.
In the prior art, the silicon wafer is heated using the heater under the state that the reverse side surface of the silicon wafer is in contact with the wafer holder, and then the ion beam is irradiated on the silicon wafer in a high temperature state. Therefore, the temperature of the silicon wafer becomes difficult to be raised up and sometimes does not reach a high temperature state because heat of the silicon wafer is transmitted to the wafer holder even if the silicon wafer is heated using the heater. When the ion beam is irradiated on the silicon wafer under such a state, sometimes optimum ion implantation can not be obtained.
Further, when the reverse side surface of the silicon wafer is in contact with the wafer holder, a stress is produced by heating between the silicon wafer and the wafer holder. Therefore, sometimes cracks, chips and warps are produced in the silicon wafer when a thermal expansion occurs in the silicon wafer as the silicon wafer is being heated. At the same time, scraping occurs between the silicon wafer and the wafer holder, and particles may be produced from the silicon wafer by the scraping to reduce the quality of the silicon wafer. On the other hand, it can be considered to employ a structure floating a silicon wafer as disclosed in Japanese Patent Application Laid-Open No. Hei 4-225256, but the simply floating of wafer can not sufficiently absorb the thermal deformation of the silicon wafer.
An object of the present invention is to provide an ion implanting apparatus which is capable of absorbing the thermal deformation of an object to be ion-implanted.
In order to attain the above-mentioned object, an ion implanting apparatus according to the present invention comprises an ion source for producing an ion beam; a process chamber for containing an object to be ion-implanted; a rotating body disposed and rotated in the process chamber; a holding means for holding the object to be ion-implanted with a spacing between an ion implanted area of the object to be ion-implanted and the holding means, the holding means being connected to the rotating body; an ion beam irradiation means for irradiating the ion beam from the ion source toward the object to be ion-implanted in the process chamber; and a heating means for heating the object to be ion-implanted in the process chamber, wherein the holding means holds the object to be ion-implanted in a state in contact with a part of a region in an outer peripheral side of the object to be ion-implanted, and blocks the object to be ion-implanted to move toward an acting direction of a centrifugal force.
Further, in order to attain the above-mentioned object, an ion implanting apparatus according to the present invention comprises an ion source for producing an ion beam; a process chamber for containing an object to be ion-implanted; a rotating body disposed and rotated in the process chamber; a holding means for holding the object to be ion-implanted with a spacing between an ion implanted area of the object to be ion-implanted and the holding means, the holding means being connected to the rotating body; an ion beam irradiation means for irradiating the ion beam from the ion source toward the object to be ion-implanted implanted in the process chamber; and a heating means for heating the object to be ion-implanted in the process chamber, wherein the holding means comprises a plurality of holding portions for holding parts of regions in an outer peripheral side of the object to be ion-implanted, a first holding portion of the plurality of holding portions holding an end surface in a peripheral side of the object to be ion-implanted to block the object to be ion-implanted to move toward an acting direction of a centrifugal force, a second holding portion holding the end surface in the peripheral side of the object to be ion-implanted to allow the object to be ion-implanted to move in a direction opposite to the acting direction of the centrifugal force. In this case, the following elements maybe added to the holding portion.
The second holding portion comprises a supporting piece for supporting the end surface in the outer peripheral side of the object to be ion-implanted; an elastic body connected to the supporting piece; and a fixing member for fixing the elastic body to the rotating body.
The second holding portion comprises a supporting piece for supporting the end surface in the outer peripheral side of the object to be ion-implanted; a first elastic body connected to the supporting piece; a supporting member for supporting an end of the first elastic body; a second elastic body connected to the supporting member; and a fixing member for fixing the second elastic body to the rotating body.
Further, in order to attain the above-mentioned object, the holding means according to the present invention comprises a holding portion for holding a part of region in an outer peripheral side of the object to be ion-implanted, and the holding portion holds a side end portion in the outer periphery of the object to be ion-implanted from both surface sides in an axial direction of the object to be ion-implanted. In this case, it is preferable that the holding portion holds a side end portion in the outer periphery of the object to be ion-implanted from both surface sides in an axial direction of the object to be ion-implanted.
When each of the ion implanting apparatus is constructed, the following elements may be added.
(1) The elastic body is formed of a coil spring.
(2) The elastic body is formed of a plate spring.
(3) Each of the first elastic body and the second elastic body is formed of a plate spring, and the plate springs are disposed so that directions of elastic forces of the plate springs become opposite to each other.
(4) A material of the holding portion is silicon or quartz when the object to be ion-implanted is formed of silicon.
(5) The ion implanting apparatus can process a silicone wafer as the object to be ion-implanted.
According to the present invention, the object to be ion-implanted is held with a spacing between an ion implanted area of the object to be ion-implanted and the holding means, and the object to be ion-implanted is held in a state in contact with a part of a region in an outer peripheral side of the object to be ion-implanted. Therefore, the object to be ion-implanted can be blocked to move toward an acting direction of a centrifugal force. When heat energy produced by the heater is transferred to the object to be ion-implanted, the heat energy is suppressed to be transferred to the other elements. Therefore, the object to be ion-implanted can be maintained at a high temperature state. Further, even if the object to be ion-implanted is thermally deformed by ion beam irradiation, the deformation can be absorbed. Accordingly, it is possible to prevent producing of particles by the thermal deformation such as thermal expansion.
Further, since the ion implanting apparatus has the structure to allow the object to be ion-implanted to move in a direction opposite to the acting direction of the centrifugal force, it is possible to maintain the object to be ion-implanted at a high temperature state and to prevent the object to be ion-implanted from being cracked, chopped and warped.
Further, in order to attain the above-mentioned object, a sample processing apparatus in accordance with the present invention comprises a process chamber for containing a sample to be processed; a rotating body disposed and rotated in the process chamber; and a holding means for holding the sample to be processed with a spacing between a processed area of the sample to be processed and the holding means, and for irradiating a beam onto the sample to be processed, the holding means being connected to said rotating body, wherein the holding means holds the sample to be processed in a state in contact with a part of a region in an outer peripheral side of the sample to be processed, and blocks the sample to be processed to move toward an acting direction of a centrifugal force.
According to the sample processing apparatus in accordance with the present invention, the object to be beam-irradiated is held with a spacing between an beam-irradiated area and the holding means, and the object to be beam-irradiated is held in a state in contact with a part of a region in an outer peripheral side of the sample to be processed. Therefore, the object to be beam-irradiated can be blocked to move toward an acting direction of a centrifugal force. When heat energy produced by the heater is transferred to the sample to be processed, the heat energy is suppressed to be transferred to the other elements. Therefore, the sample to be processed can be maintained at a high temperature state capable of being irradiated. Further, even if the object to be ion-implanted is thermally deformed by ion beam irradiation, the deformation can be absorbed. Accordingly, it is possible to prevent producing of particles by the thermal deformation such as thermal expansion.